Investigators in the field of archery, for some time, have recognized the advantages of illuminating the nock end of an arrow for bowhunting. Inasmuch as most hunting is done during low light levels when game are most active or in wilderness areas characterized by dense foliage, there has existed and remains a need for arrows offering enhanced visibility to the hunter as an aid in his or her tracking of game that, even though mortally wounded, continue to wander a considerable distance before falling. Furthermore, arrows, far from being considered expendable by the average hunter, constitute a substantial expense when unlocatable after an errant shot.
Carissimi, as evidenced in his seminal work described in U.S. Pat. No. 4,340,930, was the first to appreciate the superiority of illumination over other tracing devices or methods. Illumination, unlike audible or radio frequency signal tracking techniques, permits the archer to trace an arrow in flight, thereby enabling the observation of its trajectory to the target or its diversion therefrom as a result of contact with branches and the like which may be invisible to the naked eye. Also, audible tracking approaches, having a tendency to frighten game, preclude a hunter from attempting multiple shots. Radio frequency signal based systems, silent to the game, are not disadvantaged in this respect but, because of the necessity of a transmitter and a receiver, are of a cost prohibitive for the average hunter. Tracking devices utilizing a tracing line affixed to the arrow have numerous disadvantages, not the least of which is an increase in aerodynamic drag and the concomitant decrease in arrow velocity and accuracy.
The tracer-like quality of an illuminated arrow in flight also proves worthwhile in archer training. Oscillations or vibrations in an arrow are manifestations of either improper bow configuration or a less than optimal release by the archer. The ability to observe and discern the vibrational characteristics of an arrow on its way to the target, greatly enhanced by an illuminated nock, aids the archer in determining the cause of the malfunction so that corrective measures may be employed.
Moreover, arrows with traceability enhanced through illumination are uniquely advantageous for use in archery tournaments. Insofar as spectators must, by necessity, view the event a considerable distance from the target, their enjoyment of the competition is often lessened by an inability to see the arrow during or subsequent to its penetration into the target. Owing to their excellent visibility, a quality not shared by arrows embodied with the other aforementioned tracking approaches, illuminated arrows alone find utility in archery tournaments.
Although the advantages of illuminated arrow nocks are clear, neither archers nor archery equipment manufacturers have, as yet, embraced the concept. Viewed with an eye towards manufacturing and marketing, the illuminated nocks should be interchangeable with standard arrow nocks and manufacturable at a competitive cost. Carissimi's early work, comprised essentially of a lamp nested within an optically transparent nock, a battery and circuitry nested adjacent the nock in the elongate shaft of the arrow, and a switch on the arrow surface actuable by the archer to effect illumination of the nock prior to arrow launch, was said to be disadvantaged by its complexity including an external switch and its lack of interchangability with existing nocks.
Viewed from an archer's perspective, an illuminated nock should improve arrow visibility without any effect on the archer prior to launch or any effect on the arrow subsequent to launch. A review of the early work leads to the conclusion that these requirements have not, as yet, been satisfied. Some proposed devices require the archer to actuate a rotation switch prior to his nocking of the arrow. Apart from the inconvenience that this additional step engenders, the illuminated nock interferes with the aiming of the archer by creating a veiling luminance at the retina so as to hinder ambient light vision, thereby making target acquisition problematic, especially in low-light situations. Time-delayed switches, while ameliorating the detrimental effects of having an illuminated source adjacent the eye of the archer, necessitate that the arrow be launched a particular predetermined time after nocking.
Arrow performance is adversely affected by devices which propose switches with actuation components externally disposed on the arrow. Any such knobs, levers, buttons, slides or like protuberances disrupt the laminar flow of air around an arrow in flight to produce unacceptable turbulent flow or eddies that decrease both arrow velocity and accuracy.
Arrow performance is also affected by the weight of the arrow inasmuch as arrow velocity varies inversely with arrow mass. Consequently, it is evident that a nock minimizing the addition of weight to the arrow would be most preferred by archers.
Investigators have recognized the advantages of inertially actuated illumination. In theory, an illuminated nock so embodied would not energize until the forces imposed on the arrow during launch actuated the switch. Consequently, the archer would be saved the inconvenience of having to manually operate a switch and would be spared the hindering effects of having a bright light adjacent his or her eye while still afforded the advantage of being able to track the arrow in flight. However, in practice, an inertial switch meeting the requirements of aerodynamic design, light weight, compactness, reliability, and interchangability has not been forthcoming. Additionally, the inertial switches now known require inconvenient and expensive external devices for de-energization subsequent to inertial energization. Thus, there exists a continuing need for an illuminated nock, inertially actuated or otherwise, possessing these features.